The variational characteristics of Tibet temperature are analysed by using the monthly mean temperature data of eighteen weather stations from 1961 to 1990. The results show that monthly mean temperature is coldest during the 1960's,and is warmest during the 1980's. The variation of summer temperature is different in three areas. In Tibet, the anomalous warm may occur in different seasons, but anomalous cold is seldom. The periodicity of 22-year, 11-year, 4. 4-year and 2—3-year is significant. There is a good persistence of Tibet temperature in the late winter and summer. Temperature is easily changed in October and November.